Development of the μPPT propulsion module for STRaND a 3U CubeSat

Abstract

CubeSats to date have shown an excellent potential in providing quality science and demonstrating the use of COTS technology in space applications. A next stage in the evolution of CubeSat technology is the ability to demonstrate useable on board propulsion. Following on and building on the success of previous missions (CanX-2, ION etc), Surrey Space Centre has designed, developed and is in the process of manufacturing the propulsion flight module that will be able to provide pitch, roll and yaw around a central axis and translational movement in two axes. The module comprises of eight breech fed micro Pulsed Plasma Thrusters (μPPTs). To aid in the miniaturisation there have been two significant changes. The first was a replacement of the typical sparkplug with a contact trigger mechanism that initiates a discharge. The second was the removal of the typical Teflon TM propellant used in PPTs between the discharging electrodes. In studies at the Surrey Space Centre it was shown that discharges without the presence of Teflon TM produced 60-75% the impulsebit then discharges with the presence of Teflon TM at the parameters that were tested. The mass eroded for the plasma production was theorised to originate from the electrodes, which is similar in the mechanisms of operation to the Vacuum Arc Thruster (VAT). The module is split into three PC104 boards, two boards house four μPPTs on them and the third board is the power unit. The power unit uses award winning voltage multipliers that take the 5V CubeSat bus voltage and transforms this to 700V for the PPT high voltage capacitors. This paper focuses on the developmental work that has been conducted to construct a propulsion module for the Surrey Training Research and Nano-satellite Demonstration (STRaND) 3U CubeSat, which is due for launch in November 2011.

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